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A168197
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a(n) = 3*n - a(n-1) + 1 with n > 1, a(1)=0.
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1
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0, 7, 3, 10, 6, 13, 9, 16, 12, 19, 15, 22, 18, 25, 21, 28, 24, 31, 27, 34, 30, 37, 33, 40, 36, 43, 39, 46, 42, 49, 45, 52, 48, 55, 51, 58, 54, 61, 57, 64, 60, 67, 63, 70, 66, 73, 69, 76, 72, 79, 75, 82, 78, 85, 81, 88, 84, 91, 87, 94, 90, 97, 93, 100, 96, 103, 99, 106, 102
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OFFSET
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1,2
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LINKS
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FORMULA
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Sum_{n>=2} (-1)^(n+1)/a(n) = 5/4 - Pi/(6*sqrt(3)) - log(3)/2. - Amiram Eldar, Feb 23 2023
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MATHEMATICA
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PROG
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(Magma) I:=[0, 7, 3]; [n le 3 select I[n] else Self(n-1)+Self(n-2)-Self(n-3): n in [1..70]]; // Vincenzo Librandi, Feb 28 2012
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CROSSREFS
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KEYWORD
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nonn,easy
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AUTHOR
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EXTENSIONS
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STATUS
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approved
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